Exercise aid



FIG. 1 is a top perspective view of the exercise aid showing the design;

FIG. 2 is a right side elevation view thereof;

FIG. 3 is a front end view thereof;

FIG. 4 is a top plan view thereof;

FIG. 5 is a back end view thereof;

FIG. 6 is a left side elevation view thereof; and,

FIG. 7 is a bottom plan view thereof. 

The ornamental design for an exercise aid, as shown and described. 